1. Field of the Invention
The present invention relates to a register circuit, particularly to a register circuit including a plurality of registers, wherein an effective data is set in a selected register and the remaining registers are reset simultaneously with the setting of the effective data in the selected register.
2. Description of the Related Art
In the conventional register circuit including a plurality of registers each storing a predetermined number of bit data, each of the registers is constituted by a predetermined number of, for example, D-type flip-flop circuits, and an address signal is input to each of the registers. Also, the predetermined number of bit data is input to each of the registers.
When one of the above address signals becomes effective, the above data input to each of the registers at that time is stored in the selected register receiving the effective address signal. In this connection, the data already stored in the remaining registers receiving address signals which are not effective is not changed but maintained as is.
Thus, according to the above conventional register circuit, it is only possible to independently control the data stored in the selected register receiving the effective address signal in accordance with the value of the above input data, and the data already stored in the remaining registers receiving the address signals which are not effective is maintained without change.
Therefore, in the above register circuit, if a request is sent to set an effective data (i.e., "1") in a selected register, and to reset the remaining registers, each value of the data already stored in the registers must be monitored outside of the register circuit (e.g., each value of the above data must be successively read out to the outside or each value of the above data must be stored at the outside by, for example, programming). Then, to write new data "1" or "0" to predetermined registers, it must be determined whether the value of the new data to be written to a predetermined register is different from that of the data already stored in the corresponding register, to prevent data "1" from being simultaneously set in more than one register (i.e., to prevent a double registration).
Therefore, in the conventional register circuit, a problem arises in that a very complicated process is necessary to set the effective data in a selected register and to reset the remaining registers without generating a double registration.